RFR: 8246837: Rename WeakHandle<vm_class_loader_data> to better reflect its OopStorage association

[Erik Österlund]

Hi,

WeakHandle<vm_class_loader_data> uses the OopStorageSet::vm_weak() 
OopStorage. This is not obvious from the name. In particular, it becomes 
problematic when new weak handles are created in other areas of the VM, 
using the same OopStorage. I don't want them to go under the 
vm_class_loader_data name, when they have nothing to do with that. It 
seems more intuitive to name them vm_weak_data, reflecting which 
OopStorage they are associated with.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8246837

Webrev:
http://cr.openjdk.java.net/~eosterlund/8246837/webrev.00/

Thanks,
/Erik